This invention pertains generally to electrode leads, and more particularly to the manufacture of in-line connector assemblies for electrode leads.
In-line connector assemblies for electrode leads employing coaxial conductors have been made and used for some time. Typically, such a connector includes a connector ring coupled to the outer coiled conductor and a connector pin, located proximal to the connector ring and coupled to the inner coiled conductor. Connection of the ring and pin to their respective conductors was typically accomplished by crimping or swaging. One such connector was used on the Model 4002 pacing lead, made and sold in the United States by Medtronic, Inc.
This prior art in-line connector employed a silicone rubber insulating sleeve separating the connector pin and connector ring. This insulating sleeve was molded to the connector assembly following the attachment of the connector ring and connector pin to their appropriate conductor coils. Silicone rubber was particularly advantageous in this construction, because of its low required molding temperature, which allowed molding to take place late in the assembly of the lead, without worry of damage to the already assembled lead components due to high temperatures. Unfortunately, any defect in the molding of the sleeve resulted in the scrapping of the entire lead, as disassembly was not feasible. Other plastics such as polyurethane display greater tensile strength and rigidity, which would be beneficial in this application. However, the high required molding heat for polyurethane effectively precludes its use in an insulating sleeve molded to an already assembled lead.